The process of metaplasia is being studied in the epithelial tumor, keratoacanthoma. The localization of vitamin A in the tumor is being studied on a time sequence. In addition, the effect of various metabolic inhibitors such as Actinomycin D and Puromycin was and is being examined as to what effect these drugs have on the tumor. It was noted that Actinomycin D applied prior to vitamin A acid results in no visible observation of mucus while Actinomycin D applied after vitamin A acid applications results in a mucus production. Studies have been carried out which suggest that vitamin A acid or its metabolite is incorporated into the nucleus of keratinocytes and establishes a new direction of protein synthesis which Actinomycin D cannot change unless Actinomycin D is given before the vitamin A acid.